Reaction of 5-Substituted tetrazoles with trifluoroacetic anhydride

Article abstract of DOI:10.1134/S1070428007110218

5-Substituted tetrazoles readily react with trifluoroacetic anhydride at 20-25°C to give the corresponding 2-substituted 5-trifluoromethyl-1,3,4- oxadiazoles, in contrast to published data according to which the title compounds are converted into 1,3,4-oxadiazole derivatives on heating with carboxylic acid anhydrides or chlorides at 100-120°C. The reaction is governed not only by the rate of acylation of the tetrazole ring and temperature conditions but also by the stability of intermediate N-acyltetrazoles.

Full text of DOI:10.1134/S1070428007110218

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2007, Vol. 43, No. 11, pp. 1710–1714. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © L.I. Vereshchagin, O.N. Verkhozina, F.A. Pokatilov, S.K. Strunevich, A.G. Proidakov, V.N. Kizhnyaev, 2007, published in Zhurnal
Organicheskoi Khimii, 2007, Vol. 43, No. 11, pp. 1709–1713.
Reaction of 5-Substituted Tetrazoles
with Trifluoroacetic Anhydride
L. I. Vereshchagin, O. N. Verkhozina, F. A. Pokatilov, S. K. Strunevich,
A. G. Proidakov, and V. N. Kizhnyaev
Institute of Petroleum and Coal-Chemical Synthesis, Irkutsk State University, ul. K. Marksa 1, Irkutsk, 664003 Russia
e-mail: kizhnyaev@chem.isu.ru
Received July 21, 2006
Abstract—5-Substituted tetrazoles readily react with trifluoroacetic anhydride at 20–25°C to give the corre-
sponding 2-substituted 5-trifluoromethyl-1,3,4-oxadiazoles, in contrast to published data according to which
the title compounds are converted into 1,3,4-oxadiazole derivatives on heating with carboxylic acid anhydrides
or chlorides at 100–120°C. The reaction is governed not only by the rate of acylation of the tetrazole ring and
temperature conditions but also by the stability of intermediate N-acyltetrazoles.
DOI: 10.1134/S1070428007110218
The well known transformation of 5-substituted
tetrazoles into 1,3,4-oxadiazoles upon thermolysis in
the presence of carboxylic acid chlorides and anhy-
drides [1, 2] has some limitations which are related as
a rule to thermal stability of the initial tetrazoles, inter-
mediate compounds, and products (the reaction occurs
above 100°C). For example, reactions of 5-vinyl- and
5-[2-(dimethylamino)ethyl]tetrazoles Ib and Ic and
some other tetrazoles with aliphatic and aromatic acid
chlorides at elevated temperature are accompanied by
strong tarring. Unlike published data on the thermol-
ysis of 5-substituted tetrazoles in the presence of car-
boxylic acid chlorides and anhydrides [1, 2], we pre-
viously showed that such reactions with trifluoroacetic
anhydride readily occur at low temperature [3]. The
observed strong gas evolution suggests that the process
begins even at –5°C, and the reaction completion is
judged by the amount of released nitrogen. The reac-
tion is successful in methylene chloride, diethyl ether,
acetone, benzene, and toluene. It is advisable to use
low-boiling solvents which facilitate isolation of the
products. Under the above conditions, we succeeded in
effecting reactions with trifluoroacetic anhydride of
5-vinyl-, 5-[2-(dimethylamino)ethyl]-, 5-chloromethyl-,
and 5-(2-chloroethyl)tetrazoles Ib, Ic, Ih, and Ii, i.e.,
with those substrates which underwent tarring under
the thermolysis conditions. In addition, tetrazoles Ia
and Id–Ig, as well as bicyclic compounds Ij–Il, were
converted into the corresponding 1,3,4-oxadiazoles
(Scheme 1).
The transformation of all the above tetrazoles into
oxadiazoles is characterized by a fairly high rate at
room temperature, so that the reaction time does not
exceed 5 h. An exception was the reaction of trifluoro-
acetic anhydride with cyanomethyltetrazole Ie, where
nitrogen evolution lasted more than 24 h. Nevertheless,
the corresponding oxadiazole was isolated in a good
yield. The 13C NMR spectra of compounds IIa–IIk
contained signals in the regions δC 160–173 and 155–
Scheme 1.
R
R
N
N
N
N
H
(CF3CO)2O or CCl3COCl
COCX3
N
N
N
N
–N2
X3C
R'
N
N
O
Ia–Il
IIa–IIl, III
I, II, X = F, R = R′ = Ph (a), CH2=CH (b), Me2NCH2CH2 (c), EtOCOCH2 (d), NCCH2 (e), Me (f), MeOCH2CH2 (g), ClCH2 (h),
ClCH2CH2 (i), 2-(5-phenyl-2H-tetrazol-2-yl)ethyl (j), 2-phenyl-1,2,3-triazol-4-yl (k); R = 2-(tetrazol-5-yl)ethyl, R′ = 2-(5-trifluoro-
methyl-1,3,4-oxadiazol-2-yl)ethyl (l); III, X = Cl, R′ = Ph.
1710

REACTION OF 5-SUBSTITUTED TETRAZOLES WITH TRIFLUOROACETIC ANHYDRIDE
1711
159 ppm, which were assigned to the C2 and C5 atoms
of the 1,3,4-oxadiazole ring, respectively. In addition,
a signal at δC 116–120 ppm was observed due to
trifluoromethyl group. This signal, as well as the C5
signal, appeared as a quartet with a coupling constant
1JCF of 267–271 Hz. The 13C–19F coupling constant for
C5 was 43–46 Hz. Compounds II showed in the mass
spectra ion peaks corresponding to particular molec-
ular fragments.
conditions, in DMF at 100°C. The progress of reac-
tions was monitored by gas–liquid chromatography,
following the consumption of benzonitrile (see figure).
It is seen that 2-hydroxyethylammonium azide, piperi-
dinium azide, and diethylammonium azide exhibit en-
hanced reactivity.
The curves shown in figure provide relative esti-
mates of the degree of transformation of benzonitrile in
the presence of ammonium salt, which are not always
consistent with the yields of tetrazoles in reactions
with preliminarily prepared azides. Among the above
ammonium azides, we isolated as individual sub-
stances 2-hydroxyethylammonium azide and diethyl-
ammonium azide by mixing benzene solutions of the
amine and hydrazoic acid. 2-Hydroxyethylammonium
azide was used as the most reactive to synthesize
a series of 5-substituted tetrazoles.
We also examined the reaction of 5-phenyltetrazole
(Ia) with trichloroacetyl chloride. However, no reac-
tion occurred at room temperature. Taking into account
previously published data on the catalytic effect of
amines in the acylation of tetrazoles [4], triethylamine
or pyridine was added to the reaction mixture. In the
presence of an equimolar amount of triethylamine or
pyridine, tetrazole Ia reacted with trichloroacetyl chlo-
ride at room temperature with vigorous evolution of
nitrogen. The product was 2-phenyl-5-trichloromethyl-
1,3,4-oxadiazole (III) which was identical to a sample
prepared by reaction of Ia with trichloroacetyl chloride
at 80°C. As might be expected, the presence of
a strong electron-withdrawing group in the molecule of
acylating agent favors fast acylation of the substrate.
Intermediate N-acyltetrazoles having an electron-with-
drawing fragment are very unstable and are readily
converted into 1,3,4-oxadiazoles at a relatively low
temperature. Thus the use of highly reactive anhy-
drides makes it possible to obtain thermally unstable
oxadiazoles from labile 5-substituted tetrazoles.
EXPERIMENTAL
The NMR spectra were recorded on a Varian VXR-
1
500S spectrometer at 500 MHz for H and 126 MHz
for 13C from solutions in acetone-d6 and acetone,
respectively. The elemental compositions were deter-
mined on a FLASH EA 1112 Series CHN analyzer.
The mass spectra were obtained on an Agilent 5973N–
GC-6890 GC–MS system (injector temperature 250°C,
HP-Ultra colum). GLC analysis was performed on
a Gals chromatograph equipped with a flame ioniza-
tion detector and an HP-5 15-m capillary column (car-
rier gas nitrogen, flow rate 80 ml/min; detector tem-
perature 240°C, injector temperature 240°C, oven tem-
Most tetrazoles studied in this work were prepared
by cycloaddition of ammonium azide to the corre-
sponding nitriles. However, some nitriles decomposed
during the process because of severe conditions (tem-
perature 100–120°C; reaction time 20 h and longer). It
is known that ammonium azides often react with
nitriles much more efficiently than does sodium azide
[5]. The most reactive are ammonium azide, dimethyl-
ammonium azide, and symmetric tetramethylguanidi-
nium azide [6]. In some cases, the use of these azides
shortened the reaction time only slightly and did not
prevent the reaction mixture from tarring. With a view
to determine which azides are the most reactive and to
accelerate the process, we compared the reactivities of
a series of ammonium azides formed in situ by ex-
change reaction of amine hydrochlorides with sodium
azide. As amines we used mainly difunctional deriva-
tives: benzene-1,2-diamine, ethane-1,2-diamine, hex-
ane-1,6-diamine, 2-hydroxyethanamine, diethylamine,
and piperidine. The reactions of the corresponding
azides with benzonitrile were carried out under similar
m, %
100
1
80
60
2
3
4
5
6
7
8
40
20
0
0
100
200
300
Time, min
Plots of the concentration of benzonitrile (%) versus time in
the reactions with different azides Cat+ N3; Cat = (1) Na,
(2) 2-NH2C6H4NH3, (3) H2N(CH2)6NH3, (4) NH4,
(5 ) H2 N(CH2)2 NH3, (6 ) (CH2 )5 NH2, (7 ) Et2 NH2,
(8) HO(CH2)2NH3.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 11 2007

VERESHCHAGIN et al.
1712
perature 130°C). Diethylammonium azide and 2-hy-
droxyethylammonium azide were prepared according
to the procedure reported in [7], tetrazoles Ij and Ik
were synthesized as described in [8], and tetrazoles Ib
and Ic were obtained according to [9].
J = 267.2 Hz), 158.5 q (C5, J = 43.8 Hz), 172.2 s (C2).
Mass spectrum, m/z (Irel, %): 209 (0.7) [M]+, 165 (2.1),
95 (2.1), 69 (16.3), 58 (100), 42 (29.8). Found, %:
C 40.16; H 4.34; N 20.02. C7H10F3N3O. Calculated, %:
C 40.19; H 4.78; N 20.1. M 209.17.
Compounds IIa, IIb, and IId–IIl were synthesized
in a similar way.
Tetrazoles Ia, Id, Ie, and Ig (general procedure).
A suspension of 0.06 mol of sodium azide and
0.06 mol of 2-aminoethanol hydrochloride in 35 ml of
DMF was stirred for 30 min at 40°C, 0.06 mol of the
corresponding nitrile (or 0.03 mol of dinitrile) was
added, and the mixture was heated to 100°C and kept
for 5–7 h at that temperature. The progress of the re-
action was monitored by TLC. When the reaction was
complete, the solvent was distilled off under reduced
pressure, and the residue was treated with a solution of
sodium hydroxide to pH 9 and washed with ethyl
acetate. The aqueous solution was acidified with
hydrochloric acid to pH 2, and the precipitate was
filtered off. Otherwise, the solution was extracted with
ethyl acetate (3×10 ml), the extract was dried over
magnesium sulfate, the solvent was distilled off under
reduced pressure, and the residue was recrystallized
from ethanol.
2-Phenyl-5-trifluoromethyl-1,3,4-oxadiazole
(IIa) was obtained from 1 g (6.8 mmol) of 5-phenyl-
tetrazole (Ia) and 1.7 g (8.0 mmol) of trifluoroacetic
anhydride in 12 ml of methylene chloride. Yield 1.3 g
1
(89%), mp 49–50°C (EtOH). H NMR spectrum, δ,
ppm: 7.6–8.1 m (5H, Ph). 13C NMR spectrum, δC,
ppm: 154.1 q (C5, J = 43.6 Hz), 166.1 s (C2), 116.4 q
(CF3, J = 269.5 Hz), 122.1–133.3 m (Carom). Mass
spectrum, m/z (Irel, %): 214 (56.7) [M]+, 145 (64.7), 77
(100), 68 (43.5), 118 (3.3), 195 (3.5). Found, %:
C 50.39; H 2.41; N 12.92. C9H5F3N2O. Calculated, %:
C 50.47; H 2.34; N 13.08. M 214.15.
2-Trifluoromethyl-5-vinyl-1,3,4-oxadiazole (IIb)
was obtained from 5 g (50 mmol) of 5-vinyltetrazole
(Ib) and 11.6 g (55 mmol) of trifluoroacetic anhydride
in 115 ml of methylene chloride. Yield 6.5 g (76%),
1
bp 40°C (15 mm), nD20 = 1.3945, d420 = 1.32. H NMR
5-Phenyltetrazole (Ia). Yield 67%, mp 216°C;
spectrum, δ, ppm: 6.92 (1H, =CH), 6.45 (1H, =CH2),
6.10 (1H, =CH2). 13C NMR spectrum, δC, ppm: 118.74
(=Cα), 128.84 (=Cβ), 165.26 s (C5), 154 q (C2), 116.51 q
(CF3). Mass spectrum, m/z (Irel, %): 164 (27.9) [M]+,
145 (2.3), 95 (79), 69 (100). Found, %: C 36.54;
H 1.45; N 17.05. C5H3F3N2O. Calculated, %: C 36.59;
H 1.83; N 17.07. M 164.09.
published data [5]: mp 217–218°C.
Ethyl (tetrazol-5-yl)acetate (Id). Yield 53%,
mp 126°C; published data [4]: mp 128–130°C.
(Tetrazol-5-yl)acetonitrile (Ie). Yield 55%,
mp 115°C; published data [10]: mp 115–117°C.
5-(2-Methoxyethyl)tetrazole (Ig). Yield 45%,
mp 65–67°C; published data [4]: mp 66–67°C.
Ethyl (5-trifluoromethyl-1,3,4-oxadiazol-2-yl)-
acetate (IId) was synthesized from 1 g (6.4 mmol) of
tetrazolylacetate Id and 1.4 g (8.3 mmol) of trifluoro-
acetic anhydride in 15 ml of methylene chloride. Yield
0.87 g (61%), bp 91–92°C (7 mm), nD24 = 1.3952.
1H NMR spectrum, δ, ppm: 0.74 t (3H, CH3CH2),
3.7 q (2H, OCH2), 3.9 s (2H, CH2CO). 13C NMR spec-
trum, δC, ppm: 14.3 s (CH2CO), 32.6 s (CH3), 63.2 s
(OCH2), 117.6 q (CF3, J = 279.4 Hz), 156.9 q (C5, J =
45.1 Hz), 164.9 s (C=O), 167.1 s (C2). Mass spectrum,
m/z (Irel, %): 224 (0.5) [M]+, 205 (2.3), 179 (28), 152
(85.6), 69 (100), 42 (46.5). Found, %: C 37.41; H 2.97;
N 12.07. C7H7F3N2O3. Calculated, %: C 37.5; H 3.13;
N 12.5. M 224.14.
N,N-Dimethyl-2-(5-trifluoromethyl-1,3,4-oxa-
diazol-2-yl)ethanamine (IIc). A solution of 1.9 g
(9 mmol) of trifluoroacetic anhydride in 2 ml of meth-
ylene chloride was added dropwise to a suspension of
1.0 g (7 mmol) of tetrazole Ic in 10 ml of methylene
chloride under stirring at room temperature. The color-
less mixture gradually became homogeneous. When
the evolution of nitrogen was over, the mixture was
neutralized with a saturated solution of sodium hydro-
gen carbonate to pH 9, the aqueous phase was treated
with diethyl ether (3×10 ml), the extracts were com-
bined with the organic phase and dried over magne-
sium sulfate, the solvent was distilled off, and the
residue was distilled under reduced pressure. Yield
1.2 g (81%), bp 66°C (10 mm), nD20 = 1.3990. 1H NMR
spectrum, δ, ppm: 1.5 s (6H, CH3), 2.6 t (2H, 2-CH2),
3.0 t (2H, CH2N). 13C NMR spectrum, δC, ppm: 27.4 s
(2-CH2), 47.9 s (CH3), 58.9 s (CH2N), 120.3 q (CF3,
(5-Trifluoromethyl-1,3,4-oxadiazol-2-yl)aceto-
nitrile (IIe) was synthesized from 0.8 g (7.3 mmol) of
5-cyanomethyltetrazole Ie and 1.7 g (10.9 mmol) of
trifluoroacetic anhydride in 15 ml of methylene chlo-
ride. Yield 0.72 g (55%), mp 35°C (from EtOH).
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REACTION OF 5-SUBSTITUTED TETRAZOLES WITH TRIFLUOROACETIC ANHYDRIDE
1713
13C NMR spectrum, δC, ppm: 15.6 s (CH2), 112.7 s
(CN), 116.4 q (CF3, J = 270.4 Hz), 155.5 q (C5, J =
45.2 Hz), 172.9 s (C2). Mass spectrum, m/z (Irel, %):
177 (18.6) [M]+, 158 (4.5), 137 (1.4), 108 (100), 69
(69.1). Found, %: C 32.65; H 1.02; N 23.16.
C5H2F3N3O. Calculated, %: C 33.9; H 1.13; N 23.73.
M 177.09.
167.9 (C2). Mass spectrum, m/z (Irel, %): 199 (0.9) [M]+,
165 (100), 131 (20.5), 82 (0.9), 69 (43.7), 49 (14.9).
Found, %: C 29.65; H 1.76; N 13.71. C5H4F3ClN2O.
Calculated, %: C 29.93; H 2.00; N 13.97. M 209.55.
5-Phenyl-2-[2-(5-trifluoromethyl-1,3,4-oxadi-
azol-2-yl)ethyl]tetrazole (IIj) was obtained from 1 g
(4.1 mmol) of bistetrazole Ij and 1.5 g (7.1 mmol) of
trifluoroacetic anhydride in 15 ml of methylene chlo-
ride. Yield 0.92 g (72%), mp 77–78°C (from EtOH).
13C NMR spectrum, δC, ppm: 29.4 s (2′-CH2), 47.5 s
(CH2N), 117.2 q (CF3, J = 269.2 Hz), 126.7–130.8 m
(Carom), 156.8 q (C5′, J = 43.8 Hz), 166.3 s (C2′), 163.4 s
(C5). Found, %: C 46.32; H 2.1; N 27.1. C12H9F3N6O.
Calculated, %: C 46.45; H 2.9; N 27.1.
2-Methyl-5-trifluoromethyl-1,3,4-oxadiazole (IIf)
was synthesized from 1 g (12 mmol) of 5-methyl-
tetrazole (If) and 3.35 g (16 mmol) of trifluoroacetic
anhydride in 15 ml of methylene chloride. Yield 0.95 g
(52%), bp 26–28°C (8 mm), nD20 = 1.3585. 13C NMR
spectrum, δC, ppm: 10.8 s (CH3), 117.7 q (CF3, J =
268.8 Hz), 156.3 q (C5, J = 43.8 Hz), 168.2 s (C2).
Mass spectrum, m/z (Irel, %): 152 (27.9) [M]+, 133
(4.2), 83 (100), 69 (59.1). Found, %: C 31.34; H 1.2;
N 18.04. C4H3F3N2O. Calculated, %: C 31.58; H 1.97;
N 18.42. M 152.08.
2-(2-Phenyl-1,2,3-triazol-4-yl)-5-trifluoromethyl-
1,3,4-oxadiazole (IIk) was synthesized from 1 g
(4.7 mmol) of tetrazole Ik and 1.48 g (7 mmol) of tri-
fluoroacetic anhydride in 15 ml of methylene chloride.
Yield 1 g (76%), mp 112–114°C (from EtOH).
13C NMR spectrum, δC, ppm: 120–137 m (Carom),
140.1 s (C4′), 134.9 s (C5′), 117.4 q (CF3, J =
270.4 Hz), 155.6 q (C5, J = 46.3 Hz), 160.8 s (C2).
Mass spectrum, m/z (Irel, %): 281 (100) [M]+, 262 (3.3),
212 (1.4), 91 (49.3), 69 (13.1). Found, %: C 46.57;
H 2.03; N 24.87. C11H6F3N5O. Calculated, %: C 46.98;
H 2.14; N 24.91. M 281.20.
2-(2-Methoxyethyl)-5-trifluoromethyl-1,3,4-oxa-
diazole (IIg) was synthesized from 1 g (7.8 mmol) of
5-(2-methoxyethyl)tetrazole (Ig) and 2.15 g (10 mmol)
of trifluoroacetic anhydride in 15 ml of methylene
chloride. Yield 1.03 g (67%), bp 79–80°C (12 mm),
nD20 = 1.3895. 13C NMR spectrum, δC, ppm: 26.8 s
(5-CH2), 58.6 s (CH3O), 68.7 s (CH2O), 119.4 q (CF3,
J = 267.0 Hz), 156.2 q (C5, J = 43.7 Hz), 168.8 s (C2).
Mass spectrum, m/z (Irel, %): 181 (20), 166 (21), 137
(1.9), 69 (39.5), 45 (100). Found, %: C 35.57; H 3.12;
N 13.97. C6H7F3N2O2. Calculated, %: C 36.73; H 3.57;
N 14.29. M 196.13.
1,2-Bis(5-trifluoromethyl-1,3,4-oxadiazol-2-yl)-
ethane (IIl) was obtained from 1 g (4.1 mmol) of com-
pound Il and 1 g (5 mmol) of trifluoroacetic anhydride
in 15 ml of methylene chloride. Yield 1.1 g (60%),
1
mp 100–101°C (from EtOH). H NMR spectrum, δ,
2-Chloromethyl-5-trifluoromethyl-1,3,4-oxadia-
zole (IIh) was obtained from 1.25 g (10 mmol) of
5-chloromethyltetrazole (Ih) and 4.12 g (20 mmol) of
trifluoroacetic anhydride in 15 ml of methylene chlo-
ppm: 3.0 (2H, CH2). 13C NMR spectrum, δC, ppm:
116.1 q (CF3, J = 270.4 Hz), 21.3 s (CH2), 154.1 q
(C5, J = 43.8 Hz), 167.7 s (C2). Mass spectrum, m/z
(Irel, %): 302 (65.1) [M]+, 283 (47), 164 (4.2), 137
(0.9), 68 (1.9), 233 (100). Found, %: C 31.52; H 1.27;
N 18.42. C8H4F6N4O2. Calculated, %: C 31.79; H 1.32;
N 18.54. M 302.14.
ride. Yield 0.95 g (49%), bp 69–70°C (14 mm), nD24
=
1.3991. 13C NMR spectrum, δC, ppm: 43.7 s (CH2Cl),
116.2 q (CF3, J = 270.0 Hz), 155.6 q (C5, J = 43.8 Hz),
165.2 s (C2). Mass spectrum, m/z (Irel, %): 186 (21.8)
[M]+, 151 (2.2), 137 (2.3), 117 (100), 69 (85.5), 49
(35.5). Found, %: C 25.23; H 1.12; N 14.73.
C4H2F3ClN2O. Calculated, %: C 25.74; H 1.07;
N 15.01. M 186.52.
2-Phenyl-5-trichloromethyl-1,3,4-oxadiazole
(III). a. Trichloroacetyl chloride, 1.24 g (6.8 mmol),
was added at room temperature to a suspension of
0.5 g (3.4 mmol) of tetrazole Ia in 10 ml of methylene
chloride, and 0.34 g (3.4 mmol) of triethylamine or
0.28 g (3.4 mmol) of pyridine was then added. When
vigorous evolution of nitrogen ceased, the mixture was
neutralized to pH 9 with a saturated solution of sodium
carbonate. The organic layer was separated and washed
with water, the aqueous layer was extracted with meth-
ylene chloride (3×10 ml), the extracts were combined
with the organic phase and dried over magnesium
2-(2-Chloroethyl)-5-trifluoromethyl-1,3,4-oxadi-
azole (IIi) was obtained from 2 g (15 mmol) of 5-(2-
chloroethyl)tetrazole (Ii) and 4.7 g (22.5 mmol) of tri-
fluoroacetic anhydride in 15 ml of methylene chloride.
Yield 0.9 g (30%), bp 83°C (10 mm), nD24 = 1.4050.
1H NMR spectrum, δ, ppm: 4.1 t (2H, CH2Cl), 3.6 t
(2H, 2-CH2). 13C NMR spectrum, δC, ppm: 29.1 s
(2-CH2), 40.5 s (CH2Cl), 118.2 q (CF3), 158.1 q (C5),
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 11 2007

VERESHCHAGIN et al.
1714
2. Osipova, T.F., Koldobskii, G.I., and Ostrovskii, V.A.,
sulfate, the solvent was evaporated on a Petri dish in
air, and the residue was recrystallized from ethanol.
Yield 0.68 g (76%), mp 64–65°C (from EtOH).
Zh. Org. Khim., 1984, vol. 20, p. 2468.
3. Vereshchagin, L.I., Verkhozina, O.N., Pokatilov, F.A.,
and Kizhnyaev, V.N., Russ. J. Org. Chem., 2007,
vol. 43, p. 1575.
4. Vereshchagin, L.I., Petrov, A.V., Kizhnyaev, V.N.,
Pokatilov, F.A., and Smirnov, A.I., Russ. J. Org. Chem.,
2006, vol. 42, p. 1049.
5. Finnegan, W.G., Henry, R.A., and Lofquist, R., J. Am.
Chem. Soc., 1958, vol. 80, p. 3908.
6. Papa, A.J., J. Org. Chem., 1966, vol. 31, p. 1426.
7. Titova, I.E., Poplavskii, V.S., Koldobskii, G.I., Ostrov-
skii, V.A., Nikolaev, V.D., and Erusalimskii, G.B.,
Khim. Geterotsikl. Soedin., 1986, no. 8, p. 1086.
8. Verkhozina, O.N., Kizhnyaev, V.N., Vereshchagin, L.I.,
Rokhin, A.V., and Smirnov, A.I., Russ. J. Org. Chem.,
2003, vol. 39, p. 1792.
b. Thermolysis. A mixture of 0.5 g (3.4 mmol) of
tetrazole Ia and 1.24 g (6.8 mmol) of trichloroacetyl
chloride in 1 ml of toluene was heated to 80°C and was
then kept at that temperature until nitrogen no longer
evolved. The mixture was treated as described above
in a. Yield 0.65 g (72%), mp 65–66°C. 13C NMR spec-
trum, δC, ppm: 83.3 s (CCl3), 122.9–133.2 m (Carom),
163.3 s (C5), 167.1 s (C2). Mass spectrum, m/z (Irel, %):
262 (10.5) [M]+, 227 (45.5), 145 (17.7), 117 (1.8), 105
(100), 77 (72.7). Found, %: C 40.92; H 1.5; N 10.63.
C9H5Cl3N2O. Calculated, %: C 40.99; H 1.9; N 10.63.
M 263.51.
9. Koren’, A.O. and Gaponik, P.N., Khim. Geterotsikl.
Soedin., 1990, p. 1643.
REFERENCES
1. Huisgen, R., Sauer, J., Sturm, H.J., and Markgraf, J.H.,
10. Gryszkiewicz-Trochimowski, O., C. R. Acad. Sci., 1958,
Chem. Ber., 1960, vol. 93, p. 2106.
vol. 246, p. 2627.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 11 2007